With the innovations in nuclear medicine techniques, Lutetium 177 (177Lu) has epitomized as a revolutionary theranostic agent- with both scintigraphic and therapeutic properties. The present review focusses on the introduction of 177Lu as a promising modality for tumor diagnosis and therapy in widespread metastases . Being a shorter β-range emitter providing better irradiation of smaller tumor volumes, 177Lu- based PRRT is being increasingly used in patients with somatostatin receptor positive neuroendocrine tumors. Clinical trials with 177Lu–DOTATATE and 177Lu–DOTATOC have gained considerable interest in recent years with successful tumor regression in patients with malignant metastatic neuroendocrine tumors. Especially, therapy with 177Lu-DOTATATE PRRT has reported to significantly improve the quality of life of Gastroenteropancreatic NET patients because of higher affinity of DOTATATE for the somatostatin type 2 receptors. In addition, this review also sheds light on the diagnostic and palliative aspects of 177Lu which also serves to be an attractive candidate for the preparation of radiopharmaceuticals for radiation synovectomy of small to medium sized joints. Enlisting all the said features, 177Lu is strongly emerging as a promising theranostic agent that could possibly endow Nuclear Medicine an edge over other conventional therapies in near future.